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> we don't even really have an agreed-upon definition of life Regulated metabolism. Homeostasis. I think that's close to capturing the idea we're after. A s

by retrac 4y ago

> we don't even really have an agreed-upon definition of life Regulated metabolism. Homeostasis. I think that's close to capturing the idea we're after. A self-aware computer still has to store its bits somewhere, and get energy and material to do that, presuming it wants to stay alive. That process might as well be called metabolism. Unless it is just totally alien (heh) physics, there would be some kind of metabolism, and localized regions which create an environment suitable for that metabolism to place. That would, if nothing else, produce heat and unusual compounds.

_Algernon_ 4y ago
Are viruses alive? They aren't commonly considered to be. They don't have a regulated metabolism without parasitising on the cells of other organisms. But then again, I doubt humans would have homeostasis for long without their microflora. How is that different? Isn't a virus just a more extreme case of symbiosis? What about less extreme obligate parasites? Life defies categorization. At best you can find common markers (in addition to the ones you've mentioned, the traits required for natural selection to occur - i.e. reproduction, variation in trait, and variance in offspring - may also be of interest), but in the end it boils down to the anthropocentric notion of "things like us", which isn't very useful outside earth.
- retrac 4y ago
  It's possible a life-like system might have parts that, on their own, don't seem like-life. Human economic activity would fall under the category of "metabolism" that I used, for example. Cars are not alive either; but they, are, in the loosest sense, part of a living system. Fossil fuels for shipping food around are a part of the larger system of metabolism, ultimately enabling viruses to replicate in their human hosts. Viruses are dependent on metabolism, too; even if they can't do it themselves.

by retrac 4y ago

_Algernon_ 4y ago

Are viruses alive? They aren't commonly considered to be. They don't have a regulated metabolism without parasitising on the cells of other organisms. But then again, I doubt humans would have homeostasis for long without their microflora. How is that different? Isn't a virus just a more extreme case of symbiosis? What about less extreme obligate parasites? Life defies categorization. At best you can find common markers (in addition to the ones you've mentioned, the traits required for natural selection to occur - i.e. reproduction, variation in trait, and variance in offspring - may also be of interest), but in the end it boils down to the anthropocentric notion of "things like us", which isn't very useful outside earth.

retrac 4y ago
It's possible a life-like system might have parts that, on their own, don't seem like-life. Human economic activity would fall under the category of "metabolism" that I used, for example. Cars are not alive either; but they, are, in the loosest sense, part of a living system. Fossil fuels for shipping food around are a part of the larger system of metabolism, ultimately enabling viruses to replicate in their human hosts. Viruses are dependent on metabolism, too; even if they can't do it themselves.